I'm not a nutritionist, but I think that the reason a lot of people keep eating these kind of foods is because they ate some of it while they were young, and if they tried to eat something that wasn't as heavily seasoned it would be too bland for them.
It's like their taste buds have been beaten into submission, so they need something to give him "that kick".
I'm guilty of indulging in these kind of foods as well, every so often, but I know that when I do it, I'm harming my taste buds and won't be able to as easily pick up the subtleties of sashimi (for example) the next time that I'm in a Japanese restaurant.